1. Field of the Invention
The invention relates generally to systems and methods for efficiently extracting gas from drilling mud. In particular aspects, the invention relates to systems and methods for improving gas trap efficiency.
2. Description of the Related Art
A standard drilling process includes circulating drilling mud through a well to establish well control, cutting removal and bit cooling. When drilling through a medium containing gas, condensate or oil, hydrocarbons are released from the penetrated interval. The released hydrocarbons are then transported to the surface in the drilling mud. Additional hydrocarbons may be released into the mud from oil or condensate due to changing conditions from subsurface to surface. The amount of released hydrocarbon gas, not bound or trapped in or on the cuttings, depends on the porosity, permeability and hydrocarbon saturation of the formation.
Mud logging is a commonly used service in the hydrocarbon industry and involves the extraction and measurement of hydrocarbons which are dissolved in the drilling mud. Measurements are typically conducted at surface during drilling operations using a mass spectrometer, a gas chromatograph or a combination of both. Of particular relevance to the industry are the hydrocarbons that are released from penetrated lithological units and recorded at surface once they become evaporated into gaseous phase under atmospheric conditions. Ideally, the measured hydrocarbons are only from the milled formation and can, therefore, provide highly valuable information when correlated with corresponding depths and corrected for artifacts.
Depending on the mud and hydrocarbon combination, the amount of hydrocarbons in solution may vary, and single components may have a different solubility. Conventional hydrocarbon extraction is accomplished by feeding mud through a vessel having a mechanical agitator and sucking the evaporated hydrocarbons from the headspace of a gas trap device toward a measuring unit. Based upon the measured hydrocarbon compositions and the fluid type used for the drilling operation (i.e., water-based mud, oil-based mud, synthetic oil-based mud) features like gas/oil contacts and oil/water contacts can be determined.